The steric effect of solvent molecules in the dissolution of polyacrylonitrile from five different N,N-dimethylformamide derivatives as studied using Raman spectroscopy

Minagawa, Masahiro; Takasu, Toru; Morita, Teisuke; Shirai, Hiroaki; Fujikura, Yoshiaki; Kameda, Yasuo

doi:10.1016/0032-3861(96)82916-8

Cited by 17 publications

(12 citation statements)

References 9 publications

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“…On the other hand, the substituent size in four phosphate molecule follows the order of TMP < TEP < TCP < TBP. Due to the steric effect and molecular interaction,34 the solvent power of four solvents to PVDF follows the order of TMP > TEP > TCP > TBP.…”

Section: Resultsmentioning

confidence: 99%

“…Viscosity has a strong influence on the interdiffusion of solvent and nonsolvent during the immersion precipitation process, which then controls the kinetic aspect of membrane formation process, including both skin formation and substructure morphology 34. As shown in Table IV, the viscosities of 15 wt % PVDF casting solutions prepared with different mixed solvent, TMP–DMAc (MTMP60), TEP–DMAc (MTEP60), TCP–DMAc (MTCP60), TBP–DMAc (MTBP60), follow the order of MTBP60 > MTCP60 > MTEP60 > MTMP60, which is consistent with the trend followed by the solubility parameter difference.…”

Section: Resultsmentioning

confidence: 99%

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Effects of mixed solvents and PVDF types on performances of PVDF microporous membranes

2009

J of Applied Polymer Sci

103

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Polyvinylidene fluoride (PVDF) microporous flat membranes were cast with different kinds of PVDFs and four mixed solvents [trimethyl phosphate (TMP)-N,N-dimethylacetamide (DMAc), triethyl phosphate (TEP)-DMAc, tricresyl phosphate (TCP)-DMAc, and tri-nbutyl phosphate (TBP)-DMAc]. The effects of different commercial PVDFs (Solef V R 1015, FR 904, Kynar 761, Kynar 741, Kynar 2801) on membrane morphologies and membrane performances of PVDF/TEP-DMAc/PEG200 system were investigated. The membrane morphologies were examined by scanning electron microscopy (SEM). The membrane performances in terms of pure water flux, rejection, porosity, and mean pore radius were measured. The membrane had the high flux of 143.0 AE 0.9 L m À2 h À1 when the content of TMP in the TMP-DMAc mixed solvent reached 60 wt %, which was 2.89 times that of the membrane cast with DMAc as single solvent and was 3.36 times that of the membrane cast with TMP as single solvent. Using mixed solvent with different solvent solubility parameters, different morphologies of PVDF microporous membranes were obtained. TMP-DMAc mixed solvent and TEP-DMAc mixed solvent indicated the stronger solvent power to PVDF due to the lower solubility parameter difference of 1.45 MPa 1/2 and the prepared membranes showed the faster precipitation rate and the higher flux. The less macrovoids of the membrane prepared with TEP (60 wt %)-DMAc (40 wt %) as mixed solvent contributed to the higher elongation ratio of 96.61% AE 0.41%. Therefore, using TEP(60 wt %)-DMAc (40 wt %) as mixed solvent, the casting solution had the better solvent power to PVDF, and the membrane possessed the excellent mechanical property. The microporous membranes prepared from casting solutions with different commercial PVDFs exhibited similar morphology, but the water flux increased with the increment of polymer solution viscosity.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Effects of mixed solvents and PVDF types on performances of PVDF microporous membranes

2009

J of Applied Polymer Sci

103

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“…In the fiber applications, PAN is dissolved in a suitable solvent and spin to fibers by a wet or dry spinning process [1] . Several solvents have been used to prepare PAN spinning solutions.…”

Section: Introductionmentioning

confidence: 99%

Rheological Behaviors of Polyacrylonitrile/1-Butyl-3- Methylimidazolium Chloride Concentrated Solutions

Liu

Cheng

Zhang

et al. 2007

IJMS

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Abstract:One of the room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) was chosen to prepare the concentrated solutions of Polyacrylonitrile (PAN). The rheological behaviors of the solutions were measured with rotational rheometry under different conditions, including temperatures, concentration, and molecular weight of PAN. The solutions exhibited shear-thinning behaviors, similar to that of PAN/DMF solutions. The viscosities decreased with the increasing of shear rates. However, the viscosity decreased sharply at high shear rates when the concentration was up to 16wt%. The dependence of the viscosity on temperature was analyzed through the determination of the apparent activation energy. Unusually, the viscosity of solutions of higher concentration is lower than that of lower concentration. Similarly, the viscosity of low molecular weight PAN was higher than high molecular weight PAN at high shear rates. The dynamic rheological measurement indicates the loss modulus is much higher than storage modulus. The trend of complex viscosity is similar with the result of static rheological measurement. The interaction between PAN and ionic liquid [BMIM]Cl was discussed.

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“…Minagawa et al44 reported a shift in the Raman band from 1661 cm −1 to 1671 cm −1 on adding adiponitrile to DMF, an effect that was attributed to nitrile interference with the solvent dipole–dipole interaction. The influence of the PAN nitrile moiety here is much less.…”

Section: Resultsmentioning

confidence: 99%

Azine bridge formation during the electrografting of acrylonitrile

Easter

Taylor

2009

J. Polym. Sci. A Polym. Chem.

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We report the electrografting of polyacrylonitrile (PAN) films onto evaporated gold, silver, and copper substrates, and onto platinum foil. The FTIR spectra of the films are virtually identical to library spectra of PAN and show no evidence of the cyclization observed by some authors. Raman spectra of the same films, however, display a broad absorption band centered at $1520 cm À1 and a second band at 1096 cm À1 , which are neither present in spin-coated films of commercially obtained PAN nor are they present in the FTIR spectra. These previously unreported Raman bands are dependent on a number of factors in the electrografting process; the working electrode metal, the monomer concentration, the solvent used, and the electrochemical protocol used for cleaning the working electrode. The relative intensity of the bands was found to be strongest in films grown on platinum and weakest in those grown on gold, and stronger in thin films (\50 nm) than in thick films ([100 nm). We suggest that these new spectral features are associated with azine-linked polymer chains in a ladder-like structure close to the electrode surface as a result of the predominantly isotactic brush-like conformation of the polymer during the early stages of electrografting.

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The steric effect of solvent molecules in the dissolution of polyacrylonitrile from five different N,N-dimethylformamide derivatives as studied using Raman spectroscopy

Cited by 17 publications

References 9 publications

Effects of mixed solvents and PVDF types on performances of PVDF microporous membranes

Effects of mixed solvents and PVDF types on performances of PVDF microporous membranes

Rheological Behaviors of Polyacrylonitrile/1-Butyl-3- Methylimidazolium Chloride Concentrated Solutions

Azine bridge formation during the electrografting of acrylonitrile

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